1. Field of the Invention
The invention relates to a door lock set, more particularly to a door lock set with simultaneously retractable deadbolt and latch.
2. Description of the Related Art
U.S. Pat. No. 5,077,992 discloses a door lock set which comprises a latch with a latch driving mechanism operatively driven by an inside knob that is fixed on a spindle of the latch driving mechanism and that is disposed on an inner side of a door for extending the latch outwardly to lock the door, a deadbolt with a bolt driving mechanism operatively driven by an inside thumbturn that is fixed on a spindle of the bolt driving mechanism and that is disposed on the inner side of the door for extending the deadbolt outwardly to lock the door, a driving cam secured on the spindle of the latch driving mechanism, a follower cam secured on the spindle of the bolt driving mechanism, and a linking rod having a first end portion engaging the driving cam and a second end portion engaging the follower cam. The driving cam, the follower cam and the linking rod permit simultaneous retracting of the deadbolt and the latch when the inside knob is operated.
The latch driving mechanism is further operatively driven by an outside lever mechanism that is fixed on the spindle of the latch driving mechanism and that is disposed on an outer side of the door, while the bolt driving mechanism is further operatively driven by an outside key-operated lock unit that is fixed on the spindle of the bolt driving mechanism and that is similarly disposed on the outer side of the door. The door is opened from the outside by first inserting a key into the outside key-operated lock unit so as to unlock the latter and retract the deadbolt, and then by depressing the outside lever mechanism so as to retract the latch.
Although the above described door lock set can ease opening of a door from the inside to facilitate emergency escape from a room in case of a fire, it does not facilitate opening of the door from the outside in case of an emergency.